Using BeautifulSoup for html scraping - html

Question

So i'm trying to make a program that tells the user how far away voyager 1 is from the Earth, NASA has this info on their website here http://voyager.jpl.nasa.gov/where/index.html...
I can't seem to manage to get the information within the div, here's the div: <div id="voy1_km">Distance goes here</div>
my current program is as follows : `
import requests
from BeautifulSoup import BeautifulSoup
url = "http://voyager.jpl.nasa.gov/where/index.html"
response = requests.get(url)
html = response.content
soup = BeautifulSoup(html)
test = soup.find('div', {'id' : 'voy1_km'})
print test
So long story short, How do I get the div contents?

Answer 1

as you can see from the webpage itself, the distance keep changing which is actually driven by a Javascript. You can maybe just read the javascrip code so you don't even need to scrape to get the distance... (I hate websites using Javascript as much as you:) )
If you really want to get the number off their website. You can use Selenium.
# pip install selenium
from selenium import webdriver
import time
driver = webdriver.Firefox()
driver.get("http://voyager.jpl.nasa.gov/where/index.html")
time.sleep(5)
elem = driver.find_element_by_class_name("tr_dark")
print elem.text
driver.close()
Here is the output:
Distance from Earth
19,964,147,071 KM
133.45208042 AU
Of course, please refer to the terms&conditions of their website regarding to what level you can scrape their website and distribute the data.

Answer 2

The bigger question is why even bother scraping it. If you dive a bit deeper into the Javascript file, you can repeat its calculation in a very simple manner:
import time
epoch_0 = 1445270400
epoch_1 = 1445356800
dist_0_v1 = 19963672758.0152
dist_1_v1 = 19966727483.2612
current_time = time.time()
current_dist_km_v1 = ( ( ( current_time - epoch_0 ) / ( epoch_1 - epoch_0 ) ) * ( dist_1_v1 - dist_0_v1 ) ) + dist_0_v1
print("{:,.0f} KM".format(current_dist_km_v1))